Based on the provided contexts, Satoru Gojo was killed by Ryomen Sukuna during their battle [1] [2] [3] [5]. This event occurred after Gojo was ambushed and caught off guard by Sukuna [5]. It's also worth noting that, story-wise, Gojo's death was a deliberate narrative choice to give other characters, including Yuji, more opportunities for development and prominence [6].